Presently we do not know how and why this training is so effective. However, there are many theories and Dr. Berard had some himself. Below are listed some of the most common theories but first let’s review some basic anatomy so you will be able to better understand them.
A Brief Overview of the Ear:
The middle ear contains the body’s three smallest bones (malleus, incus, and stapes; together they are termed the ossicles,) and two of the body’s smallest muscles (tensor tympani muscle and stapedius muscle.) When sound enter the outer ear and strikes the tympanic membrane (i.e., the eardrum,) the vibration of the eardrum causes the malleus to move, which in turn moves the incus, which moves the stapes. The vibrating stapes then strikes the oval window of the inner ear (cochlea,) which then causes fluid on the cochlea to bend the tiny hair cells which the auditory nerve then interprets as various sounds.
The tensor tympani muscle and the stapedius muscle are responsible for providing the proper tension to the ossicles. Additionally, when exposed to a loud sound, the two muscles react together, which in turn restricts the movement of the ossicles. As a result, the stapes strikes against the inner ear with limited force. This is known as the acoustic reflex. This is important in protecting the person from loud and harmful sounds which could injure the auditory nerve.
Theories Related to the Middle/Inner Ear